Loud-speaker unit



March 18, 1930.

J. P. QUAM LOUD SPEAKER UNIT Filed Oct. 20, 1928 nently Patented Mar.18, 1930 UNITED STATES JAMES 2. sum, or cmcaoo, more LOUD-SPEAKER umApplication filed October so, 1928. serial No. $13,090.

This invention relates to a loud speaker unit and particularly to anelectro-magnetic device which is adapted to be connected with electricalapparatus, such as radio receiving apparatus, to effect the movement ofa vibrating member, such as a cone, whereby electrical vibrations aretranslated into atmospheric vibrations of such frequency that they areaudible to the human ear.

It is an important object of the present invention to provide a deviceof the kind described which is strong and simple in construction andcapable of being economically manufactured.

It is another important object of this invention to provide anelectro-magnetic loud s eaker unit which is of such construction t atthe armature air gap may be conveniently varied and at the same timepermaretained in a predetermined desired position.

It is another object of the invention to pro vide a device of the kinddescribed wherein the position of the armature relative to the polepieces may be conveniently varied and also permanently retained andadjusted as desired.

It is another important object of this invention to rovide a loudspeaker unit of the kind descri ed wherein the permanent magnetic memberis of generally horseshoe shape and is held in position by a clampingmember which may be also adjusted to vary the relative ositions ofthepoles of said. magnetic mem er.

It is also an important object of this iii-- vention to provideapparatus of the kind described wherein laminated pole pieces areclamped to the permanent magnet and are of such form that they, alsoprovide integral Sup speaker unit embodying the principles of thisinvention. v

Figure 2 is a top plan view thereof,

Figure 3 is an enlarged fragmentary section with arts in elevation onthe line HI -III 0 Figure 2. v

Figure 4 is a section on the line IVIV of Figure 3.

As shown on the drawings:

For purposes of illustration, I have chosen a preferred embodiment ofthe present invention wherein the operating apparatus is supported on asuitable bracket 1 which may be secured directly to a loud speakercasing (not shown) or supported in a cabinet if de sired by means of anangle bracket 2 to which said bracket 1 is secured.

Secured to and projecting laterally from the bracket'l are a. pair ofthreaded studs 3 and between these studs is positioned a horse- .shoemagnet 4, the poles or free ends of which may be drawn toward each otherin a manner which will now be described. I Engaged over the ends of thestuds 3 outside of the outer leg of-the horseshoe magnet {1: is aspanner plate 5 which is apertured for free enga ement over said studsand which is clamped against the outer face of said outer leg of thehorseshoe magnet by suitable nuts 6. Similarly engaging over the studs 3and abutting the inner faced the inner leg of the horseshoe magnet 4 isa spanner plate 7 .which is held in position against the inner face ofsaid leg of the magnet by nuts 8 which like the nuts 6 are adjustablelongitudinally on the threads of the studs 3.

orted on the inner faces of the legs of the liorseshoe magnet member 4at the free ends. of said leg are laminated pole pieces 9 which arepreferably formed of angle shaped laminationsof hi h silicon steel, thelami nations being ang e shaped to afford lateral inwardly projectingportions 9 which afi'ord cores of solenoids 10 the]. windings of whichare connected in series withthe electrical circuit output terminals-ofthe instrument with which the unit of thisinvenion is designed tocooperate. Connections from said circuit to the "series winding of saidsolenoids are shown" at 11 in Figure 4." The pole pieces 9 are securedto the legs of the horseshoe mag-' net 4 by suitable clamping meanscomprising .apertured clamping barswhich engage the outside of the legsof the magnet 4 and the inner faces of the vertical portions of the polepieces, said clamping bars being designated respectively by thereference numerals 12 and 13 and being secured together in the desiredclamping relation by bolts 14 which engage through the apertures in theclamping bars on either side of the legs of the magnet 4 and which aresecured in adjusted position relative to said bars by means of nuts 15.

The armature of the unit of this invention which is actuated by themagnetic fluctuation brought about by the flow of varying currentthrough the solenoids 10 comprises a generally triangular shaped pieceof relatively rigid silicon steel 16 which is ribbed vertically as at 16to afford additional rigidity without adding appreciably to the weightthereof. The lower corners of said armature 16 are provided withgenerally vertical slots 17 which are open at their lower ends to permitengagement over the studs 3 so that the armature 16 is supported by saidstuds. Due to the relative longitudinal movement permitted by the openend slots 17, it is obvious that the armature 16 may be adjustedvertically relative to the studs 8 and when the desired verticaladjustment is attained, it is clamped in position relative to the studs3 by means of suitable nuts and washers 18 and 19 mounted on said studs.

It is furthermore obvious that the mounting of the armature 16 makes itpossible to shift the same laterally by moving the nuts 18 and washers19 longitudinally of the threaded studs 3 and consequently affords meanswhereby the armature maybe accurately centered between the ends of thepole pieces 9. The upper or free apex of the armature 16 is rigidlyconnected by a member 20 with a vibrating member 21 which is met erablyconstructed of phosphor bronze, and the fixed end of which is securedbeneath the clamping plate 12 on the outside of the outer. leg of themagnet 4. This member 21 is suitably connected to a cone member 22 sothat when the member 21 is vibrated due to its connection with thearmature 16 through the member 20, the cone member 22-will also bevibrated and set up the desired atmospheric vibrations to make possiblethe translation of electrical impulses carried to the solenoids 10 intoaudible atmospheric vibrations.

It is obvious from the foregoing that I have provided a loud speakerunit which is simple and durable in construction and which issusceptible of economical manufacture. These desirable results areachieved by the improved method of mounting the pole pieces and by theconstruction of the pole pieces from angular laminations which makespossible the use of integral laminations Which ening the nuts 6 on thestuds 3. At the same time, as previously explained, the position of thearmature relative to the air gap, both laterally and vertically, may beconveniently adjusted and securely locked in a desired position when ithas been adjusted upon menipulation of the nuts 18 and the washers 19.All of these adjustments are simple, easily effected and do not get outof adjustment when once made. Furthermore, due to the possibility ofmaking these rigid adjustments, I am able to employ a much smaller airgap than is usual in apparatus of this kind. I am further able to dothis due to the fact that the construction of this invention permits ofthe use of a relatively rigid armature which is firmly held in a desiredadjusted position.

I am aware that many changes may be made and numerous details ofconstruction may be varied through a wide range Without departing fromthe principles of this invention, and I therefore do not purposelimiting the patent granted hereon, otherwise than necessitated by theprior art.

I claim as my invention:

1. In a loud speaker unit, a supporting bracket, a pair of spacedthreaded studs projecting laterally therefrom, a horseshoe magnetpositioned between the studs, means threaded on the studs for securingthe magnet in position relative thereto and for adjusting the relativespacing of the legs of the magnet, an armature supported by said studsand projecting between the poles of the magnet, pole pieces andsolenoids carried by sa1d magnet on both sides of the armature, acantilever connector secured at one end to the outside of one leg of themagnet, and means rig idly connecting said connector with the projectingend of the armature.

2. In a loud speaker unit, a supporting bracket, a pair of spacedthreaded studs projecting laterally therefrom, a horseshoe magnetpositioned between the studs, means threaded on the studs for securingthe m net in position relative thereto and for a .j usting the relativespacing of the legs of the 3.- In a loud speaker unit, a. supportingbracket a pair of spaced threaded studs projecting laterally therefrom,a. horseshoe magnet positioned between the studs means threaded on thestuds for securing the ma net in position relative thereto and for ajusting the relative spacin of the legs of the magnet, an armature adustably supported by said studs and projecting between t of the magnet,and means threaded on the studs for securing the armature in verticaland lateral adjustment.

4. In a loud speaker unit, a sup rting bracket, a pair of spacedthreaded stu d projecting laterally therefrom, a horseshoe magnetpositioned between the studs, means threaded on the studs for securinthe magnet in position relative thereto and or adjusting the relativespacing of the legs of the magnet,

an armature supported by sa1d studs and projecting between the poles ofthe magnet pole pieces clamped to the magnet on both si es of thearmature, solenoids carried by said pole pieces and connected in serieswith an outside electrical circuit, a cantilever connector secured atone end to the outside of one leg of the magnet, and means rigidlyconnecting said connector with the projecting end of the armature.

In testimony whereof I have hereunto subscribed my name at Chicago, CookCounty,

Illinois.

J AMIES P. QUAM.

epoles.

